Construction plates may be floor boards, such as parquet; sheathing boards, or sheets for furniture building. These plates are made of solid wood, especially doweled and glued wood, or they may consist of a core of a wood material such as MDF, HDF (medium-density fiberboard, high-density fiberboard) or floor plates onto which a real wood veneer is cemented. OSB boards (Oriented Strand Boards) are the principal sheathing boards used.
The surfaces of these plates must be sealed to protect them from environmental influences. Penetration of moisture in particular must be prevented for floor boards. The surface of the board is often painted for that purpose. Paint is relatively soft, and the paint coat is subject to wear, especially in parquet floors, so that the floor must be resealed often. In closed spaces, that is linked with unpleasant features, as the old coat of paint must be sanded off before a new one can be applied. The fine sanding dust deposits everywhere, and then must be tediously removed.
Laminated panels are sealed with a coating of synthetic resin. To produce laminated panels, a paper sheet printed with a pattern is laid on a carrier board of MDF, HDF or chipboard, on which has been laid an overlay, a layer of synthetic resin or a paper layer soaked with synthetic resin. Then the board is pressed, with heating, so that the overlay, including the paper layer, bonds to the surface of the board. For floorboards, corundum particles are incorporated in the finished overlay to increase resistance to wear. Then individual panels are sawed out of the boards so produced.
A resin is not only less expensive than paint, but also harder. Placing the paper sheet or a ready-made overlay onto the top side of the plate of wood material must be done carefully. Handling of the very thin layers is complicated and requires precisely operating machines so as to make sure that only one individual layer of the overlay is lifted from a stack. For a laminated plate, the bottom side must be given an “undercoat” that compensates for the tensile stresses produced on the plate core by the decorated layer in order to prevent bending of the plate, and especially of the panels sawed out later, in the longitudinal direction.
A parquet structure is known from EP B1-0 560 870, in which a filler resin or paint is impregnated into the interior and into the intermediate spaces of the vertical grain of the wood, under the varnish layer which forms the surface coating, so that the amount of the paint is several times greater than the amount of the parquet varnish. After the filler resin has penetrated in, the boards are preheated. After cooling they absorb the resin down to a sufficient depth to form a “barrier layer” which prevents the expensive varnish penetrating in too deeply when the parquet is later sealed. This measure provides harder surfaces than the usual sealed parquetry with the same consumption of varnish.
It is known from DE C2-37 35 368 that a powdered resin layer can be scattered on a plate of material and then pieces of inlay can be placed on that. Then the powder layer is hot-pressed to melt the resin and bond it to the plate.